Can we control our daily weather?

IMITATED EFFECTS: In this 2011 file photo, a Chinese worker fires rockets for cloud seeding in an attempt to make rain in Huangpi, China

The 2008 Olympics opening ceremony in China happened to fall during a traditionally wet season for Beijing. To avoid any crimp in the plans, China decided to shoot down any cloud that looked as though it might try to enter the city uninvited. The Beijing weather modification office (WMO) celebrated a victory: The opening ceremony went by without a drop of rain and the temperature never rose above 29 degrees Celsius. Thus, due to the modification in weather, most of the day passed with no more than a few scattered clouds. The question is whether we can really control our daily weather?

According to HowStuffWorks, Chinese research into weather control is not recent but dates back to 1958. The Chinese government’s weather modification programme launches thousands of specially designed rockets and artillery shells into the sky every year in an attempt to manipulate weather conditions. The Asia Times reports that the programme employs and trains 32,000 to 35,000 people across China, some of them farmers, who are paid to handle anti-aircraft guns and rocket launchers. These heavy-duty weapons launch pellets containing silver iodide into clouds. Silver iodide is thought to concentrate moisture and cause rain, a process known as cloud seeding.

Even in areas with very low humidity, there is some water in the sky and clouds. A rainstorm happens after moisture collects around naturally occurring particles in the air, causing the air to reach a level of saturation at which point it can no longer hold in that moisture. Cloud seeding essentially helps that process along, providing additional nuclei around which water condenses. These nuclei can be salts, calcium chloride, dry ice or silver iodide, which the Chinese use. Silver iodide is effective because its form is similar to ice crystals. Calcium chloride is often used in warm or tropical areas.

Northern China, where Beijing is located, doesn’t receive much rain. In fact, its rainfall levels are 35 per cent below the world average, and some of its water supplies are significantly polluted. The area relies heavily on cloud seeding. The government practices cloud seeding to try to produce rain for farmers, reduce drought, clear away smog, fill water basins and produce a picture-perfect opening Olympic ceremony. According to the Asia Times, China has invested heavily in this technology, using more than 12,000 anti-aircraft guns and rocket launchers in addition to about 30 planes. According to Ian O’Neill of the website University Today, the Olympic ceremony weather-control feat only took the launch of 1,104 rain dispersal rockets from 21 sites in the city.

According to Things Asian, China spends $60 to $90 million a year on weather modification, in addition to the $266 million spent from 1995 to 2003. With these weather modifications, the government plans to produce 1.7 trillion cubic feet (50 billion cubic metres) of rain a year through the practice. Zhiang Qiang, who runs the Beijing WMO, suggests that water levels in Beijing’s water basins have increased up to 13 per cent due to cloud seeding.

Some of these measures are supplemented by geoengineering weather modification options for climate change. For example, according to Edwin Cartlidge, Physics World, scientists have already proposed building fleets of massive, unmanned ships to seed clouds over earth’s oceans to provide a cooling counter to carbon dioxide-induced global warming. If cloud seeding is ultimately a way to “fake it” when guests come to visit or crops need a sprinkle, do we really want a world where we have to manually adjust the planet’s atmosphere just to stave off environmental disaster?

Like China, several other countries like Russia, Israel, Thailand, and South Africa have tried their hand at weather modification by seeding the clouds. However, they have met with mixed results. For example, Australian scientists conducted numerous experiments, discovering that static seeding didn’t appear to be effective over Australia’s plains, but it was very effective over Tasmania. In fact, according to The Associated Press, in 2003, the US National Academy of Sciences declared that 30 years of studies had not produced “convincing” evidence that weather modification works.

The fundamental concern about weather modification is whether it works. For example, would it have rained in a given area without the use of weather modification, or would it have rained less? Weather might also depend heavily on environmental conditions like temperature and cloud composition.

According to HowStuffWorks, cloud seeding is quite expensive, though potentially cheaper than other projects, like diverting rivers, building new canals or improving irrigation systems. However, there are questions about altering weather as a whole. Are some areas taking moisture out of the air that would have fallen as rain in another region? And if regions are experiencing drought due to climate change, isn’t effort better spent tackling the causes of global warming?

Despite reassurances from cloud-seeding companies and its suggested success in China, concerns also remain about human exposure to silver iodide toxicity and soil contamination. In China, wayward weather cannons have damaged property and even killed one person in May 2006. The Chinese government contends that it has improved training, licensing, and safety practices. In the end, cloud seeding has strong supporters, but it remains controversial.

(The writer is on the faculty of Indian Institute of Technology, Mandi, India)